Fluid Sim multi coloured domain
Unfortunately, what you are attempting to do isn't yet supported by the Blender Fluid Simulator. You can't have fluids with different properties/materials interact because the fluid properties and material are attributes of the domain rather than of the inflow objects.

As an alternative, you may choose to use Blender's SPH Fluid Simulator, which uses the particle system rather than the fluid sim. 
Here's a previous answer to a question very similar to yours : Different materials for each fluid inflow?